Generally, applying paint as a coating on surfaces of a structure for protecting, decorating, changing or improving the characteristics or performance of the underlying surfaces is a well-known technique. The structure may be, but not limited to, a wall, a building and an instrument. Typically, paints are made up of pigments, binders and a liquid that is used for lowering the viscosity of a paint composite so that the paint composite can be applied by spraying or spreading. The binders form surface films whereas the pigments are soluble or insoluble particles. Further, the liquid may be volatile or non-volatile and does not normally become part of a dried paint. The materials used as pigments, binders and liquids define the properties and applications of the paint. When paint possesses conducting and sensing capability, the paint becomes a functional or a smart paint. Smart paints may be classified into high-performance paints, property-transforming paints, and energy-exchanging paints. Due to the advancement in polymer science, there are many specially developed high-performance smart paints readily available in market today.
Many property-transforming smart paints may include basic property-transforming materials that can be manufactured in the form of fine particles. These fine particles may be used as pigment materials in the property-transforming smart paints, along with appropriate binders and liquids. Such property-transforming paints may be utilized for indicating a temperature level associated with a product by showing a change in color. Further, recent research in the development of energy exchanging composites, for e.g. conducting polymers, has led to the development of energy-exchanging smart paints. These energy-exchanging smart paints absorb energy from light, heat, chemical or other resources and remit photons to cause fluorescence, phosphorescence, or afterglow lighting. Moreover, such energy-exchanging smart paints are electricity conductive. For example, the energy-exchanging smart paints may be coated on a glass surface to make the glass surface electrically conductive thereby having the capability of ‘heating up the glass’.
More recently, several attempts have resulted in the development of energy-exchanging smart paints that may be used as sensors for deformation monitoring of a surface. The currently available energy-exchanging smart paints are made by immersing a piezoelectric powder in an epoxy resin. Piezoelectric ceramic particles made of lead ziconate titanate (PZT) or barium titanate (BaTIO3) are frequently used in such energy-exchanging smart paints. Once this smart paint is applied on the surface, deformations in the surface causes expansions or contractions in the piezoelectric particles in the smart paint. This in turn generates detectable electrical signals, for example a current or a voltage. These electrical signals can be subsequently interpreted in order to assess deformation levels in the surface. However, assessing directions of the surface vibrations or deformations that produce the measured voltage, remains difficult. Further, this smart paint must be coated with layers of electrodes and then poled using very high voltage to impart the sensing capability to the energy-exchanging smart paints. In addition, expensive charge amplifiers are needed to monitor the capacitive output signals of the smart paint. Moreover, the currently available energy-exchanging smart paints are complex and very expensive for practical applications.
Therefore, there is need for an alternate energy-exchanging smart paint for monitoring of an external excitation on the surface.
Skilled artisans will appreciate that elements in the figures are illustrated for simplicity and clarity and have not necessarily been drawn to scale. For example, the dimensions of some of the elements in the figures may be exaggerated relative to other elements to help to improve understanding of embodiments of the present invention.